Post on 14-Aug-2018
Moving LID to the Mainstream
Annette Lucas, PE(919) 807-6381
annette.lucas@ncdenr.gov
NC Division of Energy, Mineral and Land ResourcersStormwater Program
New LID resources: works in progress
Existing LID resourcesA status report on LID in NC
Image: NC LID Guidebook
• Hydrology
• Site Assessment
• Planning
• BMPs
• Construction
• Case Studies
Existing Resource #1: LID Guidebook for NC
Certified individuals: 112
Existing Resource #2: NC LID Cert Program
TOPICS: BMPsPolicy AnalysisCase StudiesEconomicsDesign exercises
Image: NC LID Guidebook
Existing Resource #3: ExamplesLocal Government Programs
Map: www.learnnc.org
Counties: Pender, Brunswick, New Hanover, Onslow, Pender, WakeMunis: Cape Carteret, Cedar Point, Huntersville, Midland, Wilmington *
* This is only a partial list.
Tonbo Meadows, WilmingtonMeadow & woods preservedMinimized gradingRain gardens
Images: NC LID Guidebook
Successful LID Projects
Whole Foods, North RaleighDischarges LESS after development than before.
Photos: www.sandec.com
Wilkes Co. Rest Area
All stormwater from the site is infiltrated or captured and reused.
Photos: www.ncdot.gov
Status Report: How far is LID from the mainstream?
My stormwater reviews for the past 7 years:
>1,000 projects
5 were LID (< 0.5%)
Goal: Get LID to the Mainstream
Scenarios:
1,000 projects
112 would be LID (11.2%)500 would be LID (50%)LID considered as an option on EVERY project.*
* NOTE: LID will not be required.
LID considered on every project… HOW?
NEW RESOURCES:LID definition
Storm-EZ tool
BMP Manual Updates
LID Education
NC LID Guidebook definition:
LID creates a landscape that mimics the natural hydrologic functions of
infiltration, runoff, and evapotranspiration.
1.
Pre‐
& post‐
development rainfall fates are a close match for the
90th
percentile storm event.
2.
The integrity of surface waters is maintained (hydrology, flows and structure).
A development is LID when:
What are “RAINFALL FATES?”
Before development, there are two
rainfall fates:
1.
Runoff 2.
LI fates: Infiltration, ET, EvaporationPost‐filtration discharge (bioretention
and sand filter underdrains)
After development, we add a third
fate:
3.
Treated runoff (wet pond/wetland)
Photo: www.nowiknow.com
The “Conventional”
Approach:All SW directed via pipes to a wet pond
Before:
Runoff
+
Infiltration, ET, Evaporation
After:
Treated Runoff+
Infiltration, ET, Evaporation
One way to be LIDBefore:
Runoff
+
Infiltration, ET, Evaporation
After: Runoff +
Infiltration, ET,
Evaporation
Another way to be LID
Before:
Runoff
+
Infiltration, ET, Evaporation After:
Runoff +
Infiltration,
Post‐ Filtration Discharge,
ET,
Evaporation
Do the pre‐
and post‐
LI Fates have to be a perfect match for ALL projects?
No, there will be some leeway, particularly for dense sites, tight soils & high water tables.
• Excel• Permitting tool• Hunter Freeman,
PE, Withers and Ravenel
• User inputs data about pre‐
and post‐ dev land uses and SW practices.
• Uses SCS Method to pre‐
and post‐ development rainfall fates.
• Works for both the conventional “treated runoff”
approach and LID.
BMP Manual Updates will provide:
These apply to both
LID & conventional development.
• More options
• More credit
• More infiltration designs
Disconnected BUA: (new chapter)
• Two types: Rooftop drainage & sheet flow BUA vegetated areas
• LIF credit via infiltration & ET depending on soils
• Soil prep needed in D soils
• Centerpiece of LID program
Rainwater Harvesting:
• Drafted by NCSU.
• RWH model estimates performance.
• New passive drawdown design small infiltration
or bioretention
• LIF credit via ET or dedicated use
Green Roof:
• Drafted by NCSU & University of Auckland, NZ
• LIF credit based on the PAW: plant available water in
growing medium (ET)
Photos: NCSU-BAE
Bioretention:
• Need to get started
• Promote infiltration via soil prep and underdrains
• LIF credit based on ET and infiltration
Photos: NCSU-BAE
Photo: Tyner, U of Tennessee
Photo: NCSU-BAE
Infiltration:
• Need to get started
• Test soil infiltration rates
• Soil prep to improve infiltration
• LIF credit based on infiltration capacity
Swales:
• Need to get started
• Not just for conveyance anymore
• Design as infiltration, wetland or bioretention
• LIF credit based on design
NEW Educational Resources:
LID Summit – March 26‐27, 2014Organized by the Coastal Federation
LID Technical Workshops starting May 2014Organized by the NCSU Stormwater
Group
LID –
State Technical Review Team:
Withers & RavenelNCSU Stormwater
Group
Coastal FederationLocal governmentsPrivate consultants
Division of Water Resources
YOU?